A lookup stores a list of predefined, single-column values such as countries, departments, or weekdays. These values appear as selectable options in drop-down field while building applications.
Example
A Country lookup can include values like India, Australia, UK, and USA.
A Weekdays lookup can include values like Sunday, Monday, Tuesday, and so on.
A lookup ensures users select consistent values in forms. It keeps data uniform across applications, avoids variations in entries, and reduces manual typing and spelling errors.